In motor vehicle chassis, the wheel suspensions, via which the wheels are connected to the basic structure, are usually a spring as well as a shock absorber. In this context, different possibilities are known as regards the construction of the spring (e.g. coil springs, leaf springs, torsion springs) as well as its spatial arrangement in relation to the other components of the wheel suspension, especially relative to the respectively associated shock absorber. A variant that is widely used, especially for steerable (front) wheels, is so-called MacPherson struts, in which a shock absorber is disposed within a spring constructed as a coil spring. In contrast, especially for non-steerable (rear) wheels, wheel suspensions in which a shock absorber is disposed outside a spring—constructed as a coil spring—i.e. alongside it at more or less distance, can be found to a considerable extent.
It is further known that motor vehicles can be equipped with a height-positioning device, in order that, if necessary, the ground clearance can be increased (e.g. for driving onto ramps or the like) or the basic structure can be lowered (e.g. for fuel economy during highway driving). Typically, although not imperatively, this height-positioning device engages in one of the foot points of the spring of the wheel suspension in question and changes its position, although in principle it is not decisive whether the spring foot point associated with the basic structure or else with the wheel in question is positioned. Besides pneumatic and electrical spring-foot-point positioning drives (see, for example, DE 102007051971 B4), hydraulic spring-foot-point positioning drives in particular are known, for example from DE 3223195 A1, DE 102009047100 A1. U.S. Pat. No. 5,181,696 A, EP 2301773 A1, JP 2010-149550 A and WO 2014/142160 A1. Such a hydraulic cylinder-piston arrangement associated with the respective wheel suspension is pressurized in controlled manner with hydraulic fluid by a hydraulic aggregate. In this connection, a common central hydraulic aggregate may be provided for several wheel suspensions, or else several individual, decentralized hydraulic aggregates associated with the respective wheel suspension may be provided, which respectively pressurize only one single hydraulic cylinder-piston arrangement. Such a hydraulic spring-foot-point positioning drive is disclosed as part of a motor vehicle spring strut with positionable preload by DE 10109555 A1, for example.
In view of the prior art mentioned in the foregoing, the present invention is directed toward providing a motor vehicle chassis of the type mentioned in the introduction, in which an operationally safe and efficient possibility of positioning the height of the chassis above the roadway is achieved at relatively low costs and using a particularly small installation space for the hydraulic height-positioning device.